It can still be conditional, it's just that if the custom size is not the standard size, you make a copy of the custom size instead. If paper sizes were refcounted we'd just addref the custom size object, but of course they aren't.
It can still be conditional, it's just that if the custom size is not the standard size, you make a copy of the custom size instead. If paper sizes were refcounted we'd just addref the custom size object, but of course they aren't.